Prophase of mitosis vs meiosis7/1/2023 ![]() the distribution of chiasmata is not regular, they can occur anywhere on the chromosome.in the places of crossing over, the chromosomes remain connected to each other, these places are so-called chiasmata.homologous chromosomes begin to separate, the synaptonemal complex breaks down (desynapse).Bivalents remain connected in one or more places ( chiasmata). Disruption of synaptonemal complexes occurs in it. It is initiated by desynapsis of homologous chromosomes. the probable place where the crossing over process takes place corresponds to the place of occurrence of the so-called recombination nodule (nodule).the actual exchange of DNA segments can also occur between sister chromatids, but in this case it is not recombination in the true sense of the word, since the exchanged segments carry identical genetic makeup.DNA recombination between non-sister chromatids of homologous chromosomes also takes place at this stage - crossing over (crossing over and exchange of chromosomal segments).the two-chromatid composition of individual chromosomes begins to be observed.the spiraling of the chromosomes continues, they now have the appearance of coarser fibers with unevenly staining areas.the basic purpose of the synaptonemal complex is to ensure the exact pairing of the corresponding stretches of DNA, thereby contributing to error-free recombination.they remain in this state for several days.loops of chromatin fibers extend radially from the lateral element, and the central element is connected to the lateral ones by transverse filaments.each l ateral complex represents the protein axis of on e homologous chromosome and is longitudinally attached to both sister chromatids.the complex consists of two lateral elements and a central ladder-like element in the middle.chromosomes tightly connected using a special protein structure – the synaptonemal complex. ![]() the homologous pairing process is completed.Subsequently, crossing-overs occur - recombination of parts of homologues. Recombination junctions (chiasmata) are the crossing points of non-sister chromatids. It begins with the completion of bivalents - sister chromatids are visible as so-called tetrads. ![]()
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